Slope-tunable Si nanorod arrays with enhanced antireflection and self-cleaning properties.

Slope-tunable Si nanorod arrays (NRAs) were fabricated with colloidal lithography and reactive ion etching (RIE). Sharpened NRAs fabricated by increasing the SF6/O2 flow ratio during RIE exhibit enhanced antireflection (AR) and hydrophobic properties, which are attributed to the smooth gradient in the effective refractive index of NRAs, and the enlarged water/air interface of the water drops in the NRA layers, respectively. Enhanced AR characteristics via modifying the slope of NRAs are accompanied by broad-band working ranges, omnidirectionality, and polarization insensitivity. Detailed experimental and theoretical analysis of slope-tunable NRAs should benefit the development of various self-cleaning optoelectronic devices with efficient light management.

[1]  Peng Jiang,et al.  Broadband moth-eye antireflec tion coatings on silicon , 2008 .

[2]  Daniel Poitras,et al.  Toward perfect antireflection coatings. 2. Theory. , 2004, Applied optics.

[3]  Tianyou Zhai,et al.  ZnO and ZnS Nanostructures: Ultraviolet-Light Emitters, Lasers, and Sensors , 2009 .

[4]  A. Cassie,et al.  Wettability of porous surfaces , 1944 .

[5]  K. Hane,et al.  Broadband antireflection gratings fabricated upon silicon substrates. , 1999, Optics letters.

[6]  M. Hutley,et al.  Reduction of Lens Reflexion by the “Moth Eye” Principle , 1973, Nature.

[7]  C. Pan,et al.  Improved broadband and quasi-omnidirectional anti-reflection properties with biomimetic silicon nanostructures. , 2007, Nature nanotechnology.

[8]  Peng Jiang,et al.  Bioinspired Self‐Cleaning Antireflection Coatings , 2008 .

[9]  Sadao Adachi,et al.  Optical dispersion relations for Si and Ge , 1989 .

[10]  Zhong Lin Wang,et al.  Controlled replication of butterfly wings for achieving tunable photonic properties. , 2006, Nano letters.

[11]  Yong Ding,et al.  Modifying the anti-wetting property of butterfly wings and water strider legs by atomic layer deposition coating: surface materials versus geometry , 2008, Nanotechnology.

[12]  Shuyan Xu,et al.  Si quantum dots embedded in an amorphous SiC matrix: nanophase control by non-equilibrium plasma hydrogenation. , 2010, Nanoscale.

[13]  J. Greffet,et al.  Theoretical model of the shift of the Brewster angle on a rough surface. , 1992, Optics letters.

[14]  Bai Yang,et al.  Bioinspired silicon hollow-tip arrays for high performance broadband anti-reflective and water-repellent coatings , 2009 .

[15]  O. L. Russo,et al.  High aspect ratio Bosch etching of sub-0.25 μm trenches for hyperintegration applications , 2007 .

[16]  Zongfu Yu,et al.  Optical absorption enhancement in amorphous silicon nanowire and nanocone arrays. , 2009, Nano letters.

[17]  Dmitri Golberg,et al.  Inorganic semiconductor nanostructures and their field-emission applications , 2008 .

[18]  M. Malac,et al.  Surface plasmon resonance in interacting Si nanoparticle chains. , 2010, Nanoscale.

[19]  D. Stavenga,et al.  Light on the moth-eye corneal nipple array of butterflies , 2006, Proceedings of the Royal Society B: Biological Sciences.

[20]  Lei Jiang,et al.  Bioinspired surfaces with special wettability. , 2005, Accounts of chemical research.

[21]  Juergen Jahns.  J. Turunen and F. Wyrowski (eds.), Diffractive Optics for Industrial and Commercial Applications , Akademie Verlag, Berlin, Germany, 1997. 426 pp. , 1999 .

[22]  Miko Elwenspoek,et al.  The black silicon method II: The effect of mask material and loading on the reactive ion etching of deep silicon trenches , 1995 .

[23]  G. Shen,et al.  Si nanowire semisphere-like ensembles as field emitters. , 2007, Chemical communications.

[24]  G. Jellison,et al.  Characterization and optimization of absorbing plasma-enhanced chemical vapor deposited antireflection coatings for silicon photovoltaics. , 1997, Applied optics.

[25]  G. Guillemot,et al.  A multilayer model for describing hardness variations of aged porous silicon low-dielectric-constant thin films , 2009 .